|
CHAPTER THREE ...ALAS! POOR TOM By Ray Ayres John Ketteringham has kindly invited me to add a technical appraisal of the various proposals for the repair of Great Tom mentioned in the "Lincoln Letters". This I am delighted to do The Great Tom episode is an important chapter in the saga of British bellfounding and while this historical correspondence has often been quoted in part, notably in a well-known biography of John Briant, the recent publication in Ringing World is the first time it has appeared in its entirety. REVERED TOM Great Tom was originally cast in 1610, during the reign of James I, by Henry Oldfield, the Nottingham founder, and at the time and for many years afterwards remained the largest bell in the country. Even after the casting of the heavier Great Tom of Oxford, Lincoln's Tom was still generally acknowledged as being much the superior bell. The fact that during Christmas 1827 Tom \vas found to have cracked, with the loss of those sombre resonant tones from whence he got his name was a national tragedy which might be likened to the failure of Big Ben today - and thereby hangs a tale. As with any mishap affecting a much venerated national treasure, the first reaction is subconscious disbelief followed by a desire to discover some rational reason as to why such a thing could occur. Any suggestion, no matter how implausible, that seems to offer some faint glimmer of hope for minimising the damage and preserving as much as possible of what is left is likely to be given a sympathetic hearing. In this light we can very much appreciate the pressures and responsibilities facing Edward Betham, surveyor and clerk to the Cathedral, and it is much to his credit that he consistently adopted a very rational approach to often very conflicting advice. Bellfounding at this period was at a low ebb. The Church of England itself was going through a difficult period and much of the 18th century boom in founding caused by the rise in popularity and general acceptance of English change-ringing was substantially over. Many of the old foundries, including Rudall of Gloucester, were going out of business. Eayre's foundry at St. Neots was finished as was its successor run by Edward Arnold at Leicester. Robert Taylor had moved with his sons to Oxford to concentrate on clocks and chimes. Other than Thomas Mears in London, then gaining a monopoly by buying up the goodwill of most of these old businesses, only John Briant - "a man in the Arnold tradition"- who had learned his craft at St. Neots, had first hand practical experience gained in the hey-day of 18th century founding. William Dobson, while struggling to maintain the Downham Market foundry started by his grandfather Thomas Osborne - who had been Joseph Eayre's foreman, could claim some technological descent, but Briant, still active as a clockmaker at over eighty and having sold his founding interest to Mears, might be relied upon for relatively impartial advice. Edward Betham therefore made a prudent start by consulting Briant. Briant's views that the crack was unlikely to be caused by any unintentional pressure on the bell while the clock was striking and that continued use, even with a hammer of reduced weight, might extend the fracture were both reasonable. However, it was not so easy to advise on an alternative method of setting the clock striking. Lincoln Cathedral at the time had two rings of bells. The ring of eight in St. Hugh's tower, which was opposite Tom's tower, already struck the quarters on the 4th and 7th bells and therefore the clock linkage could be run to the tenor to provide only a marginally less objectionable solution to setting the hammerwork up on 2, 5 and 8 which was the only other possibility considering the treble was also cracked. The other ring in the central tower, of which the back four were cast in 1593, being much lighter were consequently known as the Ladies' bells and in any case were a six only. Briant thought Tom's tone had deteriorated over the twenty or so years since he had first heard it and therefore suspected that the crack had been propagating for some time. He surmised that the clock hammer might have been set up to strike the bell at a tangent too far above the sound-bow and presumed the resultant crack to have extended down to the lip. Betham, in deference to Briant, assumed that he meant the old position of the hammer since the bell had been half turned on its headstock fifty years before. The records for 4th. December 1778 in fact showed that the bell was also given a new clapper for tolling at this time, which far from weighing a fantastic half a ton or more as many thought, only weighed 2 cwts 11 lbs. or a very reasonable 1/40th of the weight of the bell, also the clock hammer itself weighed 104 lbs but only exerted about 44 lbs. drop on the bell, due to the counter balance effect of the linkage, and again this was by no means excessive. The important point, however, which was noted by the astute Betham, was that the crack had occurred on the OPPOSITE SIDE Of THE BELL TO THE PRESENT POSITION Of THE HAMMER. RECONSTRUCTING TOM The question now is how big was Great Tom? There were various opinions and none of them less than 95 cwt. Briant's notes showed that the diameter was 6ft 3ins. Now the starting point for most founders is that a 2 ton bell is 5 feet in diameter and strikes middle C. Great Tom therefore weighed 40 multiplied by the cube of ( 75½//60) or about 80 cwt. Without canons and if we allow an extra 7% or 6 cwt. for the canons we get 86 cwt. which compares very closely to Briant's own estimate of no more than 88 cwt. The height of this bell would have been about 5 feet and the outer curvature of the soundbow about 1 foot radius. The clock hammer, would strike at about 45 degrees or therefore around 8½ ins. above the lip. Briant's notes give the impression that the crack extended at least 7 ins. up from the lip while the newspaper reports mention a foot, which allowing both for professional caution on the one hand and journalistic licence on the other, 8½ or 9 ins. seems a reasonable estimate and implies a position at or just above the thickest part of the soundbow which on the 1/14th scale of thickness would be about 5½ ins. thick at this point. As for Tom's voice the note it struck was 523.24Hz x 60/751/2 or about 415Hz which corresponds to Ab relative to modern standard pitch of A = 440 Hz. By the pitch standards of the time (Old Concert Pitch A=428.5Hz and Handel's fork, to which standard many organs were still tuned, was A = 427cls), however, Tom would have been reckoned to be slightly flat of A. Tom was therefore virtually identical to the Loughborough Carillon Bourdon which at Ab, standard pitch, is 76 ins. in diameter, weighs 82 cwts. and incidentally took Taylor’s two goes at casting even in 1923. The limitation in founding is not so much the size of the bell as the proven capacity of the furnace. Briant as a practical founder was very sensitive to this point. He had a lot of experience building furnaces both for himself and others, and but for his age would have been willing to build one to recast Tom. He pointed out that construction alone would cost £60. Furthermore, it was upwards of a century since a bell of this size had been cast and Great Tom of Oxford (at 140 cwts -15 qrs) had taken three castings with a new furnace and still turned out to be one of the worst of the great bells of England whereas (the original) St. Paul's great bell cast in 1709 was a success from the start. Briant was therefore strongly of the opinion that Mr. Mears' furnace in London was the only one with the proven capacity and estimated the recasting would cost about £200, which was subsequently borne out by Mears' own initial estimate (4th. February 1828). WELDERS AND CHISELLERS Although Briant was of the opinion that once a bell was cracked there was no solution other than to recast it, Edward Betham was not going to make any decisions until he had explored all avenues. There were plenty of would be repairers and advisors, many delightfully vague, but those that supplied at least an element of technical description seem to fall into two main categories. The welders and chisellers. Gas welding or braising was very much the latest technology Although Sir. J. H. Thorold of Syston Park came up with an old Italian bellfounding text that advocated something of this nature, Mr. Charles Vellom, introduced by the Rev. J. S. Blundell of Crowland Abbey, gives the best thought out approach. and obviously intended to lower the bell, if he could, and use a hydrogen and gas blow-pipe and a coke or charcoal stove. He was sensible to the risk of fire and mentions the precautionary provision of water on site. It seems however that he had mistaken the size of the bell since his comment that a 36 lb. clapper being about a thirtieth the weight of the bell would be perfectly adequate implies that he thought the bell was nearer 9 cwt. than 90 cwt. The intended use of the charcoal stove is not described, but if the idea was to use it as some kind of annealing furnace in which the bell could be placed this begins to make some sense. The oxy-hydrogen burner was based on the torch developed by Gurney. Sir Goldsworthy Gurney at this period just before the advent of railways was having a degree of success with his steam carriages which were remarkable primarily for their high-pressure water tube boilers which tested to 200 p.s.i. were normally worked at 120 p.s.i. and were technically superior to anything the locomotive engineers would do for the greater part of the century. His welding torch was a by-product of this technology and if used with an annealing furnace, could have worked for small bells. Of all the alternatives to recasting, William Dobson, writing from Downham, reckoned that this scheme was the most practical, although to attempt it on a casting the size of Great Tom would be folly. However, he did seem to have had some not dissimilar ideas which he intended to put before Sir Humphrey Davy and Professor Bland although nothing was to come of it. Today of course welding of bells is a practical proposition although Dobson's caution on something the size of Tom would still apply -notwithstanding the impracticality of lowering the complete bell to the ground because of the stone vaulting beneath it. Mr. Betham, on balance, might have found himself in sympathy with Charles Dickens who observed (in 1843) that "snorting high pressure devices were comparable to living on the first floor of a powder mill and leaning over the landing balusters with a lighted candle". Drilling out the extremities of cracks to stop propagation or filing back and dressing out completely are all old established techniques for prolonging the life of defective castings and are still used today. George Sanderson of Bennet Thorpe, Doncaster (19 January 1828) described the scheme best by advocating sawing or filing out of the crack to eliminate the jarring of the broken surfaces, which as John Potts of Disley, Stockport (14 January 1828) pointed out, would contribute to the poor tone, and then drill out the ends of the minor fissures to stop further propagation. Neither gentleman probably realised that the bell was 5½ ins. thick at the crack and that bell metal was considerable harder and more brittle than the cast iron on which such techniques were usually employed. Sanderson made an important additional point that if implemented could have given Tom new life and that was MOVE THE HAMMER TO STRIKE ON A NEW AREA. It is worth noting that, but for the sheer sizes involved Sanderson's cutting out of the cracks and stopping of the fissures carried out preparatory to Vellam's welding and annealing process and final rehanging of the bell with the hammer repositioned would at least have provided a theoretically sound technique for restoration if not without its practical difficulties. Longer term, however, Tom may still have been doomed by important factors to become apparent in the next series of events. TOM DEMISED Thomas Bishop was employed by Thomas and James Upfill of Birmingham. Birmingham was a rapidly developing centre of metal manufacture burgeoning in the wake of Matthew Boulton's Soho Foundry and the technical developments of engineers like Watt and Murdoch. Mass manufacture in Birmingham of enamelled white dials for longcase clocks, for instance, had quickly replaced the more expensive locally made brass dialwort. Local clockmakers became more assemblers of standard components made in Birmingham which were sold thorough agents like Bishop to local ironmongers and whitesmiths suck as Poole and Barrow in Lincoln. Bishop (March 1831) keen to develop any aspect of the metalwork business was quick to point out the dangers of fire from welding or soldering and advocated sweeping back the lip of the bell in a curve to take all the cracked portion out, but sti1l let the “sound run round the be11" The sixth at Peterborough had had a piece cut out in this way which at least did not make the bell sound significantly worse among the rest of the ring. Although Briant had predicted that such a course of action would involve a great deal of trouble and expense and be eventually abortive, Edward Betham obviously thought it preferable to the risk of fire and worth a try since even if it failed it would at least force the issue of recasting. Fundamentally Bishop had not realised either the extent of the cracking or the importance of the sound-bow to the tone of the bell. His proposals might serve for a minor crack at the lip, but not one extending right across the sound-bow itself. What he also did not realize, until a large piece dropped off when he started work, was that the crack continued to run round the nodal circle above the sound-bow. At this stage he returned to Birmingham leaving poor Poole and Barrow removing other sections to try to find the end of the crack. Eventually thirteen pieces broke off weighing 9½ cwt. which could be pieced together to read the latinized inscription round the lip: ABRICE RI CHARD S CLATON ARCHDIACONVS, LINCOLN LAVRENTIVS STANTON DECAVS, ROGERVS PARKER PRE the whole adding up to 8 ft in length or over ⅓ of the circumference. Such a crack would have taken some time to develop and Briant's suspicion of a gradual deterioration in tone was no doubt correct. Tom's tone, however, was now irrepairably lost for ever and the bell only fit for removal from the to\ver by smashing up. What was important, however, was the noticeable discolouration of the metal along which the crack had propagated implying poor alloying and too quick cooling in the mould which indeed suggests an inability of the furnace to raise such an amount of metal to an adequate casting temperature. Bishop's analysis of the metal from the soundbow showed nearly 30% tin to 70% copper whether this is indicative of the whole bell is doubtful, because of the poor alloying, but certainly in the region of the sound-bow the bell was much too brittle. ESSENTIALLY TOM HAD TOO MUCH TIN. PHOENIX TOM William Dobson had been scathing of the inferior quality of the metal in bells 200 or 300 years old and had consistently proposed casting and hanging of a new bell complete for £200 before removal of the old one. After a visit in July 1829, however, he pointed out that assuming Tom contained about 4 tons 11 cwt of metal, based on an average of the various estimates, and with a further 2 tons 16 cwts. from the Ladies bells, only a further 10 cwt. of metal would be required to produce the heaviest bell in the Kingdom which at 7 tons 17 cwts. would be 2 cwts, heavier than Great Tom of Oxford. He also proposed to recast the front four bells which included the broken treble, of the ring in St. Hugh's tower to provide the two bells to strike the quarters and install all three new bells in the central tower all for £385. Dobson badly wanted to do the job seeing this as his chance to cast the finest bell in the country and once it was established that Tom was irreparably damaged, he revised his quotation down to £256 (15th September 1831). It was a great shame this offer was not taken up. The resulting bell, had it been successful, would have been comparable to Manchester Town Hall hour bell or the Buckfast Abbey bourdon. Edward Betham may have been cautious because of Briant's warning about proven furnace capacity. Whatever the cause for reticence Dobson was tragically forced to sell-out to Mears in 1833 and finished his days in the poor house. Incidentally we owe much to Dobson who was the first to write down any details of his founding techniques. In 1834 Mears was finally given the job of casting a new Tom essentially to Dobson's scheme even to the extent of considering casting a bell larger than Great Tom of Oxford. In the event both the new Tom and the two quarter bells were cast out of a weight of metal made up of the original bell and the six Ladies bells plus some additional scrap copper. The total cost was just under £359 for the foundry and a contingency of just over £51 for work to the timber and traps in the central tower. The new bell was to be 6 ft 10 ins. diameter, 5⅝ ins. thick at the soundbow and to be as near as possible in the key of A (old standard). The new Great Tom started casting at 10.32 a.m. on 15th November 1834, the metal started to run at 10.361/2, took 16 minutes to fill the mould and a further 4 minutes for the excess to be run into the reservoirs. The new bell including canons weighed 5 tons 8 cwt. and was finally hung in place on the 13th April 1835 barely two years before Queen Victoria came to the throne. BEN (Son of) TOM Big Ben in many ways epitomises Victorian achievement and both the Westminster clock and its giant bell owe much to Sir Edmund Beckett Denison, Lord Grimthorpe and so for that matter does modern bellfounding. Grimthorpe later recalled "when we began the Westminster Bell business in 1855, I found there was as good as nothing of a practical kind to be learnt from books, and what little there was contradictory and some of it evidently wrong. Warners confessed they did not know how to make such large bells of the proper notes, they had previously copied all their bells from existing ones. I doubt if there was a fairly good peal of bells cast since about 1830 or perhaps earlier. Briant of Hertford, was a celebrated maker of both clocks and bells early in this century. There are some nice peals of his. The best peal of five bells I ever heard, at Castle Camps in Cambridgeshire, was by Dobson who lived at Downham but failed and died in the Charter House". Grimthorpe therefore started from scratch and found wide variations in size, thickness and weight which is born out in the Lincoln Letters with James Harrison advocating light bells for a given note such as a 10¾ cwt. ring in F (Laneham, Gainsborough) which is just possible but very light. In the event Grimthorpe was to err on the heavy side with a 1/13th scale of thickness, but his method of construction of the profile was adopted by both Warner and Mears and subsequently adapted by Taylor to give their present accepted profile. As important, however, was the composition of the metal alloy. With the help of the Royal School of Mines, Grimthorpe carried out a whole series of analysis and experiments including analysing some of the metal Mears still .had from - of all bells - old Great Tom of Lincoln and so incredibly, on this was based the specification of the metal alloy for Big Ben. The first Big Ben was set out by Grimthorpe at Warners Cripplegate Foundry, but cast at the Norton Furnaces near Stockton-on-Tees by Charles Borham. Warner's nephew William Warner, who being in partnership with a firm known as Warner, Lucas and Barret, had the necessary furnace capacity. Incidentally this was the first time the basket moulding technique was used and Warners filed the original patent on it. Pouring the metal took an hour and after a not uneventful journey to London by schooner the 16 ton monster was set up in New Palace Yard, Westminster for testing where throughout much of 1857 it rang for a quarter of an hour each week until finally it cracked! The four foot crack appeared OPPOSITE THE HAMMER where the two circular waves meet to generate the opposite antinode. Various theories were put forward for the failure but whatever the cause Warners had had enough and now demanded too high a price for recasting. George Mears, however was prepared to undertake the task at Whitechapel. The bell section was reduced and the second Big Ben was cast on the 18th February 1859 and eventually set up in the tower and started striking on the 11th July 1859. By September, however, this second bell too cracked and once again OPPOSITE THE HAMMER! In 1862 the Astronomer Royal recommended a reduction in the weight of the hammer from 6½ to 4 cwts., a platform to be placed underneath the bell in case any bits dropped off and the bell to be turned relative to the hammer so that the crack falls at a node rather than an antinode for the fundamental mode of vibration. So all 13½ tons of Big Ben remains to this day. Alas! poor Great Tom might have survived the same way but for an earlier lack of understanding of sound wave generation. TOM'S LEGACY Lord Grimthorpe was very critical of Mears casting and made much of the fact that the second casting of Big Ben was undoubtedly porous in places. However, just as important was the alloy. From his experimental results presented to the Royal Institution in 1857, Grimthorpe showed that the old founders generally used about 25% tin (3 to 1) or sometimes, as in Great Tom, a little more. This, however, was much too brittle to be safe. Current practice at the time used much less tin than this and for the Westminster Bells he specified 24%. (22 to 7). Subsequently, however, he rethought these proportions on the basis of 'chemical equivalents' to give more natural alloying properties and a true chemical combination of 6 atoms of copper to one of tin which taking into account the relative atomic weights gives 23.5% tin (13 to 4). Most founders, however, preferred as little as 22% (3½ to 1) as it made the metal much softer and easier for tuning. Grimthorpe himself, while admitting doubts over his original specification for the Westminster bells, was never prepared to go this far and finally advocated a lower limit of 23% tin. The inevitable conclusion is. that both Big Bens and their venerable ancestor old Great Tom of Lincoln to which they owed much, all cracked the same way -OPPOSITE THE HAMMER -and all had too much tin. The two larger bells cast since, both by Taylors, the 14¾ ton Great George for Liverpool Cathedral and the present "largest bell in the British Empire" Great Paul for St. Paul's Cathedral at nearly 16¾ tons have all been more prudent in their tin content. This we owe to old Great Tom of Lincoln.
|
